The ability to proficiently communicate through writing is critical to succeed in school, in the work place, and n civic life. Compared to studies of beginning reading, predictors of reading disabilities, and effective intervention reading components, much less is known about beginning writing and individual differences in writing development. in the proposed research, we will capitalize on the existing ethnically and economically diverse database and sample from the previously funded Florida Center for Learning Disabilities to address 4 specific aims. First, we will examine developmental trajectories of writing for more than 800 students from 1st-6th grade to examine the relations between reading and writing achievement across the elementary years. Second, in this sample, we will examine the extent to which writing performance and disability can be predicted by cognitive, instructional, and home environmental factors. Through the existing database, existing videotapes of literacy instruction, the collection of longitudinal data through 6th grade, and the Florida Progress Monitoring and Reporting Network database (PMRN) we will have data for this sample on cognitive factors (e.g., oral language, reading, writing, self regulation), early instructional environments related to reading and writing, and early home literacy. Third, we will utilize the instructional database and videotapes of instruction to validate malleable targets for early writing instruction. Fourth, we will identify two new cohorts of first grade students (approximately 660 students) to causally examine the impact of first grade instruction in micro-level writing (e.g., transcription and spelling) and macro-level writing (e.g., text structure, self-regulation) through an experimental study. In this experimental study we will evaluate differences in response to instruction based on children's language, literacy, and self-regulation skills. The results of the proposed project will provide important information on written expression development and early writing instruction for children with LD, identifying key mechanisms for early intervention in writing.